FEM simulation and comparison of PMN-PT single crystals based phased array ultrasonic transducer by alternating current poling and direct current poling.

The Finite element modeling (FEM) simulation and comparison of electroacoustic properties for alternating current poling (ACP) phased arrays and direct current poling (DCP) phased arrays were investigated. The simulated electrical impedance reveals that the effective working bandwidth of ACP phased arrays is wider than that of DCP phased arrays as a whole. Besides, the ACP phased arrays have a higher effective electromechanical coupling coefficient k compared to DCP arrays, which indicates that higher electromechanical conversion capacity is obtained. The average value of the ratio of longitudinal displacement R for ACP phased arrays is larger than that of DCP arrays, indicating that the longitudinal transmission efficiency of acoustic energy can be enhanced by using the ACP method. The simulation results of crosstalk are consistent with the results of vibration modal analysis. The coupling effect of transverse vibration for ACP phased arrays is weaker than that of DCP arrays, leading to reduce the interaction between the adjacent elements. The crosstalk of the ACP arrays is -11.87 dB, 0.91 dB lower than that of DCP arrays. The pulse-echo response of ACP phased arrays is 7.2% broader -6 dB bandwidth, 0.79 dB higher relative sensitivity compared to the DCP phased arrays, which prove that the longitudinal resolution and penetration depth of the ultrasonic imaging can be improved by using the ACP arrays. Besides, the consequences of the beam profile illustrate that the maximum acoustic pressure of ACP arrays is 13.8% higher than that of DCP arrays and the directivity of ACP array is slightly better than that of DCP arrays.